The project will attack the problem of lead breakage by developing a totally implanted cardiac pacemaker which has no leads. A totally implanted pulse generator will transmit pacing pulses to a myocardial electrode sutured on the heart by electromagnetic induction. The electrode assembly will have circuitry that will transform the energy to a form suitable for stimulating the heart. The system will be entirely inside the body, and will be powered by a nuclear or lithium source. Research in the present grant period on R wave sensing will be continued. The effects of particular electrodes and disease states will be studied in more detail.